Improved quantization methods in color error diffusion

Color error diffusion can be classified into two types, namely: vector erro r diffusion and scalar error diffusion, according to the underlying quantiz ation methods. Compared to scalar error diffusion, vector error diffusion i s typically superior in overall image qualify. However, if requires signifi cantly more computation. In addition, it may occasionally introduce boundar y artifacts. A color band, at a width of a few pixels to tens of pixels, ma y appear along the edges. in this paper, we propose two improvements in qua ntization for color error diffusion. First, we introduce an algorithm, whic h we call semivector quantization, to reduce the computational complexity o f vector error diffusion. Second, we present a simple yet effective method for reducing boundary artifacts. (C) 1999 SPIE and IS&T.